iBeacon sample filtering by a modified central hr samples

[Ignacio]

Hi,

I am trying to filter an iBeacon sample using a modified version of the central_hr_code.

Changes on the central_hr_code:

Added 128-bit UUID definition:

#define BT_UUID_IBEACON_VAL \
	BT_UUID_128_ENCODE(0x18ee1516, 0x016b, 0x4bec, 0xad96, 0xbcb96d166e97)

/** @brief Throughput Service UUID. */
#define BT_UUID_IBEACON                                                     \
	BT_UUID_DECLARE_128(BT_UUID_IBEACON_VAL)
	
static struct bt_uuid *uuid128 = BT_UUID_IBEACON;

Added 128-bit filter. Commented out hr filter:

    err = bt_scan_filter_add(BT_SCAN_FILTER_TYPE_UUID, uuid128);
	if (err) {
		printk("Scanning filters cannot be set\n");

		return;
	}


	//err = bt_scan_filter_add(BT_SCAN_FILTER_TYPE_UUID, BT_UUID_HRS);
	//if (err) {
	//	printk("Scanning filters cannot be set (err %d)\n", err);

	//	return;
	//}

Commented out PHY CODED features:

	/* Use active scanning and disable duplicate filtering to handle any
	 * devices that might update their advertising data at runtime. */
	struct bt_le_scan_param scan_param = {
		.type     = BT_LE_SCAN_TYPE_ACTIVE,
		.interval = BT_GAP_SCAN_FAST_INTERVAL,
		.window   = BT_GAP_SCAN_FAST_WINDOW,
        //  Option to use PHY CODED for range extension
	//	.options  = BT_LE_SCAN_OPT_CODED | BT_LE_SCAN_OPT_NO_1M
	};

No changes have been made on the iBeacon side. Why the central device cannot filter the iBeacon UUID? At the moment I don't have any filter match report while scanning.

Thanks

[Edvin]

Hello,

The first thing I think of is whether you remembered to add the line:

err = bt_scan_filter_enable(BT_SCAN_UUID_FILTER, false);

And check the return value of this. I tested briefly using the central_uart sample, where I just replaced the UUID that I searched for with the iBeacon UUID, and it worked fine here.

Best regards,

Edvin

[Ignacio]

Any update?

[Edvin]

As mentioned, I tested it by only swapping the UUID in the filter, and that works for me. Perhaps you can send me the  projects that you are using (beacon and scanner) so that I can have a look?

Best regards,

Edvin

[Ignacio]

I am using nRF Connect SDK v1.7.1. So your test should be a modified version of the sample centrar_hr_coded. The central sample should filter 128-bit ibeaon UUID. The peripheral ibeacon sample runs the original code.

Have you tested this on your side? Could you share the code here so I get it running?

[Ignacio]

Hi Edvin,

Can you share your test code here? I think it is better to share a healthy version for others to come.

Many Thanks

[Edvin]

Sorry for the late reply. I tested this using the samples peripheral_uart and central_uart found in NCSv1.7.1\nrf\samples\bluetooth\

And I changed the peripheral's main.c file with this one:

Fullscreen main_peripheral.c Download

/*
 * Copyright (c) 2018 Nordic Semiconductor ASA
 *
 * SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
 */

/** @file
 *  @brief Nordic UART Bridge Service (NUS) sample
 */
#include "uart_async_adapter.h"

#include <zephyr/types.h>
#include <zephyr.h>
#include <drivers/uart.h>
#include <usb/usb_device.h>

#include <device.h>
#include <soc.h>

#include <bluetooth/bluetooth.h>
#include <bluetooth/uuid.h>
#include <bluetooth/gatt.h>
#include <bluetooth/hci.h>

#include <bluetooth/services/nus.h>

#include <dk_buttons_and_leds.h>

#include <settings/settings.h>

#include <stdio.h>

#include <logging/log.h>

#define BT_UUID_IBEACON_VAL \
	BT_UUID_128_ENCODE(0x18ee1516, 0x016b, 0x4bec, 0xad96, 0xbcb96d166e97)

#define LOG_MODULE_NAME peripheral_uart
LOG_MODULE_REGISTER(LOG_MODULE_NAME);

#define STACKSIZE CONFIG_BT_NUS_THREAD_STACK_SIZE
#define PRIORITY 7

#define DEVICE_NAME CONFIG_BT_DEVICE_NAME
#define DEVICE_NAME_LEN	(sizeof(DEVICE_NAME) - 1)

#define RUN_STATUS_LED DK_LED1
#define RUN_LED_BLINK_INTERVAL 1000

#define CON_STATUS_LED DK_LED2

#define KEY_PASSKEY_ACCEPT DK_BTN1_MSK
#define KEY_PASSKEY_REJECT DK_BTN2_MSK

#define UART_BUF_SIZE CONFIG_BT_NUS_UART_BUFFER_SIZE
#define UART_WAIT_FOR_BUF_DELAY K_MSEC(50)
#define UART_WAIT_FOR_RX CONFIG_BT_NUS_UART_RX_WAIT_TIME

static K_SEM_DEFINE(ble_init_ok, 0, 1);

static struct bt_conn *current_conn;
static struct bt_conn *auth_conn;

static const struct device *uart;
static struct k_work_delayable uart_work;

struct uart_data_t {
	void *fifo_reserved;
	uint8_t data[UART_BUF_SIZE];
	uint16_t len;
};

static K_FIFO_DEFINE(fifo_uart_tx_data);
static K_FIFO_DEFINE(fifo_uart_rx_data);

static const struct bt_data ad[] = {
	BT_DATA_BYTES(BT_DATA_FLAGS, (BT_LE_AD_GENERAL | BT_LE_AD_NO_BREDR)),
	BT_DATA(BT_DATA_NAME_COMPLETE, DEVICE_NAME, DEVICE_NAME_LEN),
};

static const struct bt_data sd[] = {
	BT_DATA_BYTES(BT_DATA_UUID128_ALL, BT_UUID_IBEACON_VAL),
};

#if CONFIG_BT_NUS_UART_ASYNC_ADAPTER
UART_ASYNC_ADAPTER_INST_DEFINE(async_adapter);
#else
static const struct device *const async_adapter;
#endif

static void uart_cb(const struct device *dev, struct uart_event *evt, void *user_data)
{
	ARG_UNUSED(dev);

	static uint8_t *current_buf;
	static size_t aborted_len;
	static bool buf_release;
	struct uart_data_t *buf;
	static uint8_t *aborted_buf;

	switch (evt->type) {
	case UART_TX_DONE:
		LOG_DBG("tx_done");
		if ((evt->data.tx.len == 0) ||
		    (!evt->data.tx.buf)) {
			return;
		}

		if (aborted_buf) {
			buf = CONTAINER_OF(aborted_buf, struct uart_data_t,
					   data);
			aborted_buf = NULL;
			aborted_len = 0;
		} else {
			buf = CONTAINER_OF(evt->data.tx.buf, struct uart_data_t,
					   data);
		}

		k_free(buf);

		buf = k_fifo_get(&fifo_uart_tx_data, K_NO_WAIT);
		if (!buf) {
			return;
		}

		if (uart_tx(uart, buf->data, buf->len, SYS_FOREVER_MS)) {
			LOG_WRN("Failed to send data over UART");
		}

		break;

	case UART_RX_RDY:
		LOG_DBG("rx_rdy");
		buf = CONTAINER_OF(evt->data.rx.buf, struct uart_data_t, data);
		buf->len += evt->data.rx.len;
		buf_release = false;

		if (buf->len == UART_BUF_SIZE) {
			k_fifo_put(&fifo_uart_rx_data, buf);
		} else if ((evt->data.rx.buf[buf->len - 1] == '\n') ||
			  (evt->data.rx.buf[buf->len - 1] == '\r')) {
			k_fifo_put(&fifo_uart_rx_data, buf);
			current_buf = evt->data.rx.buf;
			buf_release = true;
			uart_rx_disable(uart);
		}

		break;

	case UART_RX_DISABLED:
		LOG_DBG("rx_disabled");
		buf = k_malloc(sizeof(*buf));
		if (buf) {
			buf->len = 0;
		} else {
			LOG_WRN("Not able to allocate UART receive buffer");
			k_work_reschedule(&uart_work, UART_WAIT_FOR_BUF_DELAY);
			return;
		}

		uart_rx_enable(uart, buf->data, sizeof(buf->data),
			       UART_WAIT_FOR_RX);

		break;

	case UART_RX_BUF_REQUEST:
		LOG_DBG("rx_buf_request");
		buf = k_malloc(sizeof(*buf));
		if (buf) {
			buf->len = 0;
			uart_rx_buf_rsp(uart, buf->data, sizeof(buf->data));
		} else {
			LOG_WRN("Not able to allocate UART receive buffer");
		}

		break;

	case UART_RX_BUF_RELEASED:
		LOG_DBG("rx_buf_released");
		buf = CONTAINER_OF(evt->data.rx_buf.buf, struct uart_data_t,
				   data);
		if (buf_release && (current_buf != evt->data.rx_buf.buf)) {
			k_free(buf);
			buf_release = false;
			current_buf = NULL;
		}

		break;

	case UART_TX_ABORTED:
			LOG_DBG("tx_aborted");
			if (!aborted_buf) {
				aborted_buf = (uint8_t *)evt->data.tx.buf;
			}

			aborted_len += evt->data.tx.len;
			buf = CONTAINER_OF(aborted_buf, struct uart_data_t,
					   data);

			uart_tx(uart, &buf->data[aborted_len],
				buf->len - aborted_len, SYS_FOREVER_MS);

		break;

	default:
		break;
	}
}

static void uart_work_handler(struct k_work *item)
{
	struct uart_data_t *buf;

	buf = k_malloc(sizeof(*buf));
	if (buf) {
		buf->len = 0;
	} else {
		LOG_WRN("Not able to allocate UART receive buffer");
		k_work_reschedule(&uart_work, UART_WAIT_FOR_BUF_DELAY);
		return;
	}

	uart_rx_enable(uart, buf->data, sizeof(buf->data), UART_WAIT_FOR_RX);
}

static bool uart_test_async_api(const struct device *dev)
{
	const struct uart_driver_api *api =
			(const struct uart_driver_api *)dev->api;

	return (api->callback_set != NULL);
}

static int uart_init(void)
{
	int err;
	int pos;
	struct uart_data_t *rx;
	struct uart_data_t *tx;

	uart = device_get_binding(CONFIG_BT_NUS_UART_DEV);
	if (!uart) {
		return -ENXIO;
	}

	if (IS_ENABLED(CONFIG_USB)) {
		err = usb_enable(NULL);
		if (err) {
			LOG_ERR("Failed to enable USB");
			return err;
		}
	}

	rx = k_malloc(sizeof(*rx));
	if (rx) {
		rx->len = 0;
	} else {
		return -ENOMEM;
	}

	k_work_init_delayable(&uart_work, uart_work_handler);


	if (IS_ENABLED(CONFIG_BT_NUS_UART_ASYNC_ADAPTER) && !uart_test_async_api(uart)) {
		/* Implement API adapter */
		uart_async_adapter_init(async_adapter, uart);
		uart = async_adapter;
	}

	err = uart_callback_set(uart, uart_cb, NULL);
	if (err) {
		LOG_ERR("Cannot initialize UART callback");
		return err;
	}

	if (IS_ENABLED(CONFIG_UART_LINE_CTRL)) {
		LOG_INF("Wait for DTR");
		while (true) {
			uint32_t dtr = 0;

			uart_line_ctrl_get(uart, UART_LINE_CTRL_DTR, &dtr);
			if (dtr) {
				break;
			}
			/* Give CPU resources to low priority threads. */
			k_sleep(K_MSEC(100));
		}
		LOG_INF("DTR set");
		err = uart_line_ctrl_set(uart, UART_LINE_CTRL_DCD, 1);
		if (err) {
			LOG_WRN("Failed to set DCD, ret code %d", err);
		}
		err = uart_line_ctrl_set(uart, UART_LINE_CTRL_DSR, 1);
		if (err) {
			LOG_WRN("Failed to set DSR, ret code %d", err);
		}
	}

	tx = k_malloc(sizeof(*tx));

	if (tx) {
		pos = snprintf(tx->data, sizeof(tx->data),
			       "Starting Nordic UART service example\r\n");

		if ((pos < 0) || (pos >= sizeof(tx->data))) {
			k_free(tx);
			LOG_ERR("snprintf returned %d", pos);
			return -ENOMEM;
		}

		tx->len = pos;
	} else {
		return -ENOMEM;
	}

	err = uart_tx(uart, tx->data, tx->len, SYS_FOREVER_MS);
	if (err) {
		LOG_ERR("Cannot display welcome message (err: %d)", err);
		return err;
	}

	return uart_rx_enable(uart, rx->data, sizeof(rx->data), 50);
}

static void connected(struct bt_conn *conn, uint8_t err)
{
	char addr[BT_ADDR_LE_STR_LEN];

	if (err) {
		LOG_ERR("Connection failed (err %u)", err);
		return;
	}

	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));
	LOG_INF("Connected %s", log_strdup(addr));

	current_conn = bt_conn_ref(conn);

	dk_set_led_on(CON_STATUS_LED);
}

static void disconnected(struct bt_conn *conn, uint8_t reason)
{
	char addr[BT_ADDR_LE_STR_LEN];

	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));

	LOG_INF("Disconnected: %s (reason %u)", log_strdup(addr), reason);

	if (auth_conn) {
		bt_conn_unref(auth_conn);
		auth_conn = NULL;
	}

	if (current_conn) {
		bt_conn_unref(current_conn);
		current_conn = NULL;
		dk_set_led_off(CON_STATUS_LED);
	}
}

#ifdef CONFIG_BT_NUS_SECURITY_ENABLED
static void security_changed(struct bt_conn *conn, bt_security_t level,
			     enum bt_security_err err)
{
	char addr[BT_ADDR_LE_STR_LEN];

	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));

	if (!err) {
		LOG_INF("Security changed: %s level %u", log_strdup(addr),
			level);
	} else {
		LOG_WRN("Security failed: %s level %u err %d", log_strdup(addr),
			level, err);
	}
}
#endif

static struct bt_conn_cb conn_callbacks = {
	.connected    = connected,
	.disconnected = disconnected,
#ifdef CONFIG_BT_NUS_SECURITY_ENABLED
	.security_changed = security_changed,
#endif
};

#if defined(CONFIG_BT_NUS_SECURITY_ENABLED)
static void auth_passkey_display(struct bt_conn *conn, unsigned int passkey)
{
	char addr[BT_ADDR_LE_STR_LEN];

	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));

	LOG_INF("Passkey for %s: %06u", log_strdup(addr), passkey);
}

static void auth_passkey_confirm(struct bt_conn *conn, unsigned int passkey)
{
	char addr[BT_ADDR_LE_STR_LEN];

	auth_conn = bt_conn_ref(conn);

	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));

	LOG_INF("Passkey for %s: %06u", log_strdup(addr), passkey);
	LOG_INF("Press Button 1 to confirm, Button 2 to reject.");
}


static void auth_cancel(struct bt_conn *conn)
{
	char addr[BT_ADDR_LE_STR_LEN];

	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));

	LOG_INF("Pairing cancelled: %s", log_strdup(addr));
}


static void pairing_confirm(struct bt_conn *conn)
{
	char addr[BT_ADDR_LE_STR_LEN];

	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));

	bt_conn_auth_pairing_confirm(conn);

	LOG_INF("Pairing confirmed: %s", log_strdup(addr));
}


static void pairing_complete(struct bt_conn *conn, bool bonded)
{
	char addr[BT_ADDR_LE_STR_LEN];

	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));

	LOG_INF("Pairing completed: %s, bonded: %d", log_strdup(addr),
		bonded);
}


static void pairing_failed(struct bt_conn *conn, enum bt_security_err reason)
{
	char addr[BT_ADDR_LE_STR_LEN];

	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));

	LOG_INF("Pairing failed conn: %s, reason %d", log_strdup(addr),
		reason);
}


static struct bt_conn_auth_cb conn_auth_callbacks = {
	.passkey_display = auth_passkey_display,
	.passkey_confirm = auth_passkey_confirm,
	.cancel = auth_cancel,
	.pairing_confirm = pairing_confirm,
	.pairing_complete = pairing_complete,
	.pairing_failed = pairing_failed
};
#else
static struct bt_conn_auth_cb conn_auth_callbacks;
#endif

static void bt_receive_cb(struct bt_conn *conn, const uint8_t *const data,
			  uint16_t len)
{
	int err;
	char addr[BT_ADDR_LE_STR_LEN] = {0};

	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, ARRAY_SIZE(addr));

	LOG_INF("Received data from: %s", log_strdup(addr));

	for (uint16_t pos = 0; pos != len;) {
		struct uart_data_t *tx = k_malloc(sizeof(*tx));

		if (!tx) {
			LOG_WRN("Not able to allocate UART send data buffer");
			return;
		}

		/* Keep the last byte of TX buffer for potential LF char. */
		size_t tx_data_size = sizeof(tx->data) - 1;

		if ((len - pos) > tx_data_size) {
			tx->len = tx_data_size;
		} else {
			tx->len = (len - pos);
		}

		memcpy(tx->data, &data[pos], tx->len);

		pos += tx->len;

		/* Append the LF character when the CR character triggered
		 * transmission from the peer.
		 */
		if ((pos == len) && (data[len - 1] == '\r')) {
			tx->data[tx->len] = '\n';
			tx->len++;
		}

		err = uart_tx(uart, tx->data, tx->len, SYS_FOREVER_MS);
		if (err) {
			k_fifo_put(&fifo_uart_tx_data, tx);
		}
	}
}

static struct bt_nus_cb nus_cb = {
	.received = bt_receive_cb,
};

void error(void)
{
	dk_set_leds_state(DK_ALL_LEDS_MSK, DK_NO_LEDS_MSK);

	while (true) {
		/* Spin for ever */
		k_sleep(K_MSEC(1000));
	}
}

#ifdef CONFIG_BT_NUS_SECURITY_ENABLED
static void num_comp_reply(bool accept)
{
	if (accept) {
		bt_conn_auth_passkey_confirm(auth_conn);
		LOG_INF("Numeric Match, conn %p", (void *)auth_conn);
	} else {
		bt_conn_auth_cancel(auth_conn);
		LOG_INF("Numeric Reject, conn %p", (void *)auth_conn);
	}

	bt_conn_unref(auth_conn);
	auth_conn = NULL;
}

void button_changed(uint32_t button_state, uint32_t has_changed)
{
	uint32_t buttons = button_state & has_changed;

	if (auth_conn) {
		if (buttons & KEY_PASSKEY_ACCEPT) {
			num_comp_reply(true);
		}

		if (buttons & KEY_PASSKEY_REJECT) {
			num_comp_reply(false);
		}
	}
}
#endif /* CONFIG_BT_NUS_SECURITY_ENABLED */

static void configure_gpio(void)
{
	int err;

#ifdef CONFIG_BT_NUS_SECURITY_ENABLED
	err = dk_buttons_init(button_changed);
	if (err) {
		LOG_ERR("Cannot init buttons (err: %d)", err);
	}
#endif /* CONFIG_BT_NUS_SECURITY_ENABLED */

	err = dk_leds_init();
	if (err) {
		LOG_ERR("Cannot init LEDs (err: %d)", err);
	}
}

void main(void)
{
	int blink_status = 0;
	int err = 0;

	configure_gpio();

	err = uart_init();
	if (err) {
		error();
	}

	bt_conn_cb_register(&conn_callbacks);

	if (IS_ENABLED(CONFIG_BT_NUS_SECURITY_ENABLED)) {
		bt_conn_auth_cb_register(&conn_auth_callbacks);
	}

	err = bt_enable(NULL);
	if (err) {
		error();
	}

	LOG_INF("Bluetooth initialized");

	k_sem_give(&ble_init_ok);

	if (IS_ENABLED(CONFIG_SETTINGS)) {
		settings_load();
	}

	err = bt_nus_init(&nus_cb);
	if (err) {
		LOG_ERR("Failed to initialize UART service (err: %d)", err);
		return;
	}

	err = bt_le_adv_start(BT_LE_ADV_CONN, ad, ARRAY_SIZE(ad), sd,
			      ARRAY_SIZE(sd));
	if (err) {
		LOG_ERR("Advertising failed to start (err %d)", err);
		return;
	}

	for (;;) {
		dk_set_led(RUN_STATUS_LED, (++blink_status) % 2);
		k_sleep(K_MSEC(RUN_LED_BLINK_INTERVAL));
	}
}

void ble_write_thread(void)
{
	/* Don't go any further until BLE is initialized */
	k_sem_take(&ble_init_ok, K_FOREVER);

	for (;;) {
		/* Wait indefinitely for data to be sent over bluetooth */
		struct uart_data_t *buf = k_fifo_get(&fifo_uart_rx_data,
						     K_FOREVER);

		if (bt_nus_send(NULL, buf->data, buf->len)) {
			LOG_WRN("Failed to send data over BLE connection");
		}

		k_free(buf);
	}
}

K_THREAD_DEFINE(ble_write_thread_id, STACKSIZE, ble_write_thread, NULL, NULL,
		NULL, PRIORITY, 0, 0);

and the central's main.c file with this one:

Fullscreen main_central.c Download

/*
 * Copyright (c) 2018 Nordic Semiconductor ASA
 *
 * SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
 */

/** @file
 *  @brief Nordic UART Service Client sample
 */

#include <errno.h>
#include <zephyr.h>
#include <sys/byteorder.h>
#include <sys/printk.h>

#include <bluetooth/bluetooth.h>
#include <bluetooth/hci.h>
#include <bluetooth/conn.h>
#include <bluetooth/uuid.h>
#include <bluetooth/gatt.h>

#include <bluetooth/services/nus.h>
#include <bluetooth/services/nus_client.h>
#include <bluetooth/gatt_dm.h>
#include <bluetooth/scan.h>

#include <settings/settings.h>

#include <drivers/uart.h>

#include <logging/log.h>

#define LOG_MODULE_NAME central_uart
LOG_MODULE_REGISTER(LOG_MODULE_NAME);

#define BT_UUID_IBEACON_VAL \
	BT_UUID_128_ENCODE(0x18ee1516, 0x016b, 0x4bec, 0xad96, 0xbcb96d166e97)

#define BT_UUID_IBEACON                                                     \
	BT_UUID_DECLARE_128(BT_UUID_IBEACON_VAL)

/* UART payload buffer element size. */
#define UART_BUF_SIZE 20

#define KEY_PASSKEY_ACCEPT DK_BTN1_MSK
#define KEY_PASSKEY_REJECT DK_BTN2_MSK

#define NUS_WRITE_TIMEOUT K_MSEC(150)
#define UART_WAIT_FOR_BUF_DELAY K_MSEC(50)
#define UART_RX_TIMEOUT 50

static const struct device *uart;
static struct k_work_delayable uart_work;

K_SEM_DEFINE(nus_write_sem, 0, 1);

struct uart_data_t {
	void *fifo_reserved;
	uint8_t  data[UART_BUF_SIZE];
	uint16_t len;
};

static K_FIFO_DEFINE(fifo_uart_tx_data);
static K_FIFO_DEFINE(fifo_uart_rx_data);

static struct bt_conn *default_conn;
static struct bt_nus_client nus_client;

static void ble_data_sent(uint8_t err, const uint8_t *const data, uint16_t len)
{
	struct uart_data_t *buf;

	/* Retrieve buffer context. */
	buf = CONTAINER_OF(data, struct uart_data_t, data);
	k_free(buf);

	k_sem_give(&nus_write_sem);

	if (err) {
		LOG_WRN("ATT error code: 0x%02X", err);
	}
}

static uint8_t ble_data_received(const uint8_t *const data, uint16_t len)
{
	int err;

	for (uint16_t pos = 0; pos != len;) {
		struct uart_data_t *tx = k_malloc(sizeof(*tx));

		if (!tx) {
			LOG_WRN("Not able to allocate UART send data buffer");
			return BT_GATT_ITER_CONTINUE;
		}

		/* Keep the last byte of TX buffer for potential LF char. */
		size_t tx_data_size = sizeof(tx->data) - 1;

		if ((len - pos) > tx_data_size) {
			tx->len = tx_data_size;
		} else {
			tx->len = (len - pos);
		}

		memcpy(tx->data, &data[pos], tx->len);

		pos += tx->len;

		/* Append the LF character when the CR character triggered
		 * transmission from the peer.
		 */
		if ((pos == len) && (data[len - 1] == '\r')) {
			tx->data[tx->len] = '\n';
			tx->len++;
		}

		err = uart_tx(uart, tx->data, tx->len, SYS_FOREVER_MS);
		if (err) {
			k_fifo_put(&fifo_uart_tx_data, tx);
		}
	}

	return BT_GATT_ITER_CONTINUE;
}

static void uart_cb(const struct device *dev, struct uart_event *evt, void *user_data)
{
	ARG_UNUSED(dev);

	static uint8_t *current_buf;
	static size_t aborted_len;
	static bool buf_release;
	struct uart_data_t *buf;
	static uint8_t *aborted_buf;

	switch (evt->type) {
	case UART_TX_DONE:
		if ((evt->data.tx.len == 0) ||
		    (!evt->data.tx.buf)) {
			return;
		}

		if (aborted_buf) {
			buf = CONTAINER_OF(aborted_buf, struct uart_data_t,
					   data);
			aborted_buf = NULL;
			aborted_len = 0;
		} else {
			buf = CONTAINER_OF(evt->data.tx.buf,
					   struct uart_data_t,
					   data);
		}

		k_free(buf);

		buf = k_fifo_get(&fifo_uart_tx_data, K_NO_WAIT);
		if (!buf) {
			return;
		}

		if (uart_tx(uart, buf->data, buf->len, SYS_FOREVER_MS)) {
			LOG_WRN("Failed to send data over UART");
		}

		break;

	case UART_RX_RDY:
		buf = CONTAINER_OF(evt->data.rx.buf, struct uart_data_t, data);
		buf->len += evt->data.rx.len;
		buf_release = false;

		if (buf->len == UART_BUF_SIZE) {
			k_fifo_put(&fifo_uart_rx_data, buf);
		} else if ((evt->data.rx.buf[buf->len - 1] == '\n') ||
			  (evt->data.rx.buf[buf->len - 1] == '\r')) {
			k_fifo_put(&fifo_uart_rx_data, buf);
			current_buf = evt->data.rx.buf;
			buf_release = true;
			uart_rx_disable(uart);
		}

		break;

	case UART_RX_DISABLED:
		buf = k_malloc(sizeof(*buf));
		if (buf) {
			buf->len = 0;
		} else {
			LOG_WRN("Not able to allocate UART receive buffer");
			k_work_reschedule(&uart_work, UART_WAIT_FOR_BUF_DELAY);
			return;
		}

		uart_rx_enable(uart, buf->data, sizeof(buf->data),
			       UART_RX_TIMEOUT);

		break;

	case UART_RX_BUF_REQUEST:
		buf = k_malloc(sizeof(*buf));
		if (buf) {
			buf->len = 0;
			uart_rx_buf_rsp(uart, buf->data, sizeof(buf->data));
		} else {
			LOG_WRN("Not able to allocate UART receive buffer");
		}

		break;

	case UART_RX_BUF_RELEASED:
		buf = CONTAINER_OF(evt->data.rx_buf.buf, struct uart_data_t,
				   data);
		if (buf_release && (current_buf != evt->data.rx_buf.buf)) {
			k_free(buf);
			buf_release = false;
			current_buf = NULL;
		}

		break;

	case UART_TX_ABORTED:
			if (!aborted_buf) {
				aborted_buf = (uint8_t *)evt->data.tx.buf;
			}

			aborted_len += evt->data.tx.len;
			buf = CONTAINER_OF(aborted_buf, struct uart_data_t,
					   data);

			uart_tx(uart, &buf->data[aborted_len],
				buf->len - aborted_len, SYS_FOREVER_MS);

		break;

	default:
		break;
	}
}

static void uart_work_handler(struct k_work *item)
{
	struct uart_data_t *buf;

	buf = k_malloc(sizeof(*buf));
	if (buf) {
		buf->len = 0;
	} else {
		LOG_WRN("Not able to allocate UART receive buffer");
		k_work_reschedule(&uart_work, UART_WAIT_FOR_BUF_DELAY);
		return;
	}

	uart_rx_enable(uart, buf->data, sizeof(buf->data), UART_RX_TIMEOUT);
}

static int uart_init(void)
{
	int err;
	struct uart_data_t *rx;

	uart = device_get_binding(DT_LABEL(DT_NODELABEL(uart0)));
	if (!uart) {
		LOG_ERR("UART binding failed");
		return -ENXIO;
	}

	rx = k_malloc(sizeof(*rx));
	if (rx) {
		rx->len = 0;
	} else {
		return -ENOMEM;
	}

	k_work_init_delayable(&uart_work, uart_work_handler);

	err = uart_callback_set(uart, uart_cb, NULL);
	if (err) {
		return err;
	}

	return uart_rx_enable(uart, rx->data, sizeof(rx->data),
			      UART_RX_TIMEOUT);
}

static void discovery_complete(struct bt_gatt_dm *dm,
			       void *context)
{
	struct bt_nus_client *nus = context;
	LOG_INF("Service discovery completed");

	bt_gatt_dm_data_print(dm);

	bt_nus_handles_assign(dm, nus);
	bt_nus_subscribe_receive(nus);

	bt_gatt_dm_data_release(dm);
}

static void discovery_service_not_found(struct bt_conn *conn,
					void *context)
{
	LOG_INF("Service not found");
}

static void discovery_error(struct bt_conn *conn,
			    int err,
			    void *context)
{
	LOG_WRN("Error while discovering GATT database: (%d)", err);
}

struct bt_gatt_dm_cb discovery_cb = {
	.completed         = discovery_complete,
	.service_not_found = discovery_service_not_found,
	.error_found       = discovery_error,
};

static void gatt_discover(struct bt_conn *conn)
{
	int err;

	if (conn != default_conn) {
		return;
	}

	err = bt_gatt_dm_start(conn,
			       BT_UUID_NUS_SERVICE,
			       &discovery_cb,
			       &nus_client);
	if (err) {
		LOG_ERR("could not start the discovery procedure, error "
			"code: %d", err);
	}
}

static void exchange_func(struct bt_conn *conn, uint8_t err, struct bt_gatt_exchange_params *params)
{
	if (!err) {
		LOG_INF("MTU exchange done");
	} else {
		LOG_WRN("MTU exchange failed (err %" PRIu8 ")", err);
	}
}

static void connected(struct bt_conn *conn, uint8_t conn_err)
{
	char addr[BT_ADDR_LE_STR_LEN];
	int err;

	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));

	if (conn_err) {
		LOG_INF("Failed to connect to %s (%d)", log_strdup(addr),
			conn_err);

		if (default_conn == conn) {
			bt_conn_unref(default_conn);
			default_conn = NULL;

			err = bt_scan_start(BT_SCAN_TYPE_SCAN_ACTIVE);
			if (err) {
				LOG_ERR("Scanning failed to start (err %d)",
					err);
			}
		}

		return;
	}

	LOG_INF("Connected: %s", log_strdup(addr));

	static struct bt_gatt_exchange_params exchange_params;

	exchange_params.func = exchange_func;
	err = bt_gatt_exchange_mtu(conn, &exchange_params);
	if (err) {
		LOG_WRN("MTU exchange failed (err %d)", err);
	}

	err = bt_conn_set_security(conn, BT_SECURITY_L2);
	if (err) {
		LOG_WRN("Failed to set security: %d", err);

		gatt_discover(conn);
	}

	err = bt_scan_stop();
	if ((!err) && (err != -EALREADY)) {
		LOG_ERR("Stop LE scan failed (err %d)", err);
	}
}

static void disconnected(struct bt_conn *conn, uint8_t reason)
{
	char addr[BT_ADDR_LE_STR_LEN];
	int err;

	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));

	LOG_INF("Disconnected: %s (reason %u)", log_strdup(addr),
		reason);

	if (default_conn != conn) {
		return;
	}

	bt_conn_unref(default_conn);
	default_conn = NULL;

	err = bt_scan_start(BT_SCAN_TYPE_SCAN_ACTIVE);
	if (err) {
		LOG_ERR("Scanning failed to start (err %d)",
			err);
	}
}

static void security_changed(struct bt_conn *conn, bt_security_t level,
			     enum bt_security_err err)
{
	char addr[BT_ADDR_LE_STR_LEN];

	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));

	if (!err) {
		LOG_INF("Security changed: %s level %u", log_strdup(addr),
			level);
	} else {
		LOG_WRN("Security failed: %s level %u err %d", log_strdup(addr),
			level, err);
	}

	gatt_discover(conn);
}

static struct bt_conn_cb conn_callbacks = {
	.connected = connected,
	.disconnected = disconnected,
	.security_changed = security_changed
};

static void scan_filter_match(struct bt_scan_device_info *device_info,
			      struct bt_scan_filter_match *filter_match,
			      bool connectable)
{
	char addr[BT_ADDR_LE_STR_LEN];

	bt_addr_le_to_str(device_info->recv_info->addr, addr, sizeof(addr));

	LOG_INF("Filters matched. Address: %s connectable: %d",
		log_strdup(addr), connectable);
}

static void scan_connecting_error(struct bt_scan_device_info *device_info)
{
	LOG_WRN("Connecting failed");
}

static void scan_connecting(struct bt_scan_device_info *device_info,
			    struct bt_conn *conn)
{
	default_conn = bt_conn_ref(conn);
}

static int nus_client_init(void)
{
	int err;
	struct bt_nus_client_init_param init = {
		.cb = {
			.received = ble_data_received,
			.sent = ble_data_sent,
		}
	};

	err = bt_nus_client_init(&nus_client, &init);
	if (err) {
		LOG_ERR("NUS Client initialization failed (err %d)", err);
		return err;
	}

	LOG_INF("NUS Client module initialized");
	return err;
}

BT_SCAN_CB_INIT(scan_cb, scan_filter_match, NULL,
		scan_connecting_error, scan_connecting);

static int scan_init(void)
{
	int err;
	struct bt_scan_init_param scan_init = {
		.connect_if_match = 0,
	};

	bt_scan_init(&scan_init);
	bt_scan_cb_register(&scan_cb);

	err = bt_scan_filter_add(BT_SCAN_FILTER_TYPE_UUID, BT_UUID_IBEACON);
	if (err) {
		LOG_ERR("Scanning filters cannot be set (err %d)", err);
		return err;
	}

	err = bt_scan_filter_enable(BT_SCAN_UUID_FILTER, false);
	if (err) {
		LOG_ERR("Filters cannot be turned on (err %d)", err);
		return err;
	}

	LOG_INF("Scan module initialized");
	return err;
}


static void auth_cancel(struct bt_conn *conn)
{
	char addr[BT_ADDR_LE_STR_LEN];

	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));

	LOG_INF("Pairing cancelled: %s", log_strdup(addr));
}


static void pairing_confirm(struct bt_conn *conn)
{
	char addr[BT_ADDR_LE_STR_LEN];

	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));

	bt_conn_auth_pairing_confirm(conn);

	LOG_INF("Pairing confirmed: %s", log_strdup(addr));
}


static void pairing_complete(struct bt_conn *conn, bool bonded)
{
	char addr[BT_ADDR_LE_STR_LEN];

	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));

	LOG_INF("Pairing completed: %s, bonded: %d", log_strdup(addr),
		bonded);
}


static void pairing_failed(struct bt_conn *conn, enum bt_security_err reason)
{
	char addr[BT_ADDR_LE_STR_LEN];

	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));

	LOG_WRN("Pairing failed conn: %s, reason %d", log_strdup(addr),
		reason);
}

static struct bt_conn_auth_cb conn_auth_callbacks = {
	.cancel = auth_cancel,
	.pairing_confirm = pairing_confirm,
	.pairing_complete = pairing_complete,
	.pairing_failed = pairing_failed
};

void main(void)
{
	int err;

	err = bt_conn_auth_cb_register(&conn_auth_callbacks);
	if (err) {
		LOG_ERR("Failed to register authorization callbacks.");
		return;
	}

	err = bt_enable(NULL);
	if (err) {
		LOG_ERR("Bluetooth init failed (err %d)", err);
		return;
	}
	LOG_INF("Bluetooth initialized");

	if (IS_ENABLED(CONFIG_SETTINGS)) {
		settings_load();
	}

	bt_conn_cb_register(&conn_callbacks);

	int (*module_init[])(void) = {uart_init, scan_init, nus_client_init};
	for (size_t i = 0; i < ARRAY_SIZE(module_init); i++) {
		err = (*module_init[i])();
		if (err) {
			return;
		}
	}

	printk("Starting Bluetooth Central UART example\n");


	err = bt_scan_start(BT_SCAN_TYPE_SCAN_ACTIVE);
	if (err) {
		LOG_ERR("Scanning failed to start (err %d)", err);
		return;
	}

	LOG_INF("Scanning successfully started");

	for (;;) {
		/* Wait indefinitely for data to be sent over Bluetooth */
		struct uart_data_t *buf = k_fifo_get(&fifo_uart_rx_data,
						     K_FOREVER);

		err = bt_nus_client_send(&nus_client, buf->data, buf->len);
		if (err) {
			LOG_WRN("Failed to send data over BLE connection"
				"(err %d)", err);
		}

		err = k_sem_take(&nus_write_sem, NUS_WRITE_TIMEOUT);
		if (err) {
			LOG_WRN("NUS send timeout");
		}
	}
}

My central's log looks something like this:

Test it and see if you get the same.

Best regards,

Edvin

[Ignacio]

Thanks, I will have a look at it and come back with an answer.